Chapter 14, Problem 16A

Interpretation Introduction

Interpretation: The microscopic process that takes place when a solid melts has to be described.

Concept introduction: During the process of melting, energy goes exclusively to change the state of a substance; it does not change the temperature of a substance. Melting is an isothermal process because the substance remains constant at the same temperature.

Answer to Problem 16A

Melting of solid takes place because upon the addition of heat, the particles moves faster and faster until they began to come separately causing them to move in a random motion which has the least resistance.

Explanation of Solution

In solid, individual particles are closely packed because the intermolecular forces could not be overcome by the energy of the particles. When extra energy is supplied, particles have sufficient energy to move around but not sufficient energy to separate and the formation of liquid phase starts. In liquid phase, the particles are in contact with each other and are able to move around each other.

When a solid is melted, the liquid phase is obtained. The intermolecular distance in liquid is greater than the intermolecular distance in solid. In simple words, during the process of melting the molecules move apart. Due to this, the strength of intermolecular attraction decreases.

Conclusion

Melting of solid takes place because upon the addition of heat, the particles moves faster and faster until they began to come separately causing them to move in a random motion.